Dual naming is a policy for the naming of geographical landmarks, in which an official name is adopted that combines two previous names. Usually, the context is a conflict over which of the two previous names is most appropriate.
In several countries, dual naming is used where a native people and a colonial settler community have previously used two names, for example the Denali naming dispute in the US.
In Australia, a dual naming policy is used to name landmarks that are of significance to the Indigenous Australians, but for which the most common name is European. For example, the landmark with the indigenous name Uluru and European name Ayers Rock is now officially named Uluru / Ayers Rock.
Similarly, many places in New Zealand have dual Maori and English names, such as Aoraki/Mount Cook. The practise of officially giving certain New Zealand places dual names began in the 1920s, but dual names have become much more common in the 1990s and 2000s, in part due to treaty settlements.
"Derry/Londonderry" has been used unofficially to circumvent the Derry/Londonderry name dispute, in which Irish nationalists used "Derry" and Ulster unionists use "Londonderry" for the city and county in Northern Ireland. The "Derry stroke Londonderry" spoken form of this has in turn engendered the city's nickname "Stroke City".
In Romania, the city of Cluj was renamed Cluj-Napoca for political reasons in the 1970s, as the communist government wanted to emphasize the city's Roman origins.
Another example of the phenomenon can be seed in the name of the capital of the Spanish Basque Country, Vitoria-Gasteiz. This combines the city's Spanish name of Vitoria and Basque name of Gasteiz.
The official name of the bilingual (German and French) Swiss town of Biel/Bienne is the combination of its German name (Biel) and its French name (Bienne).
In Finland, many towns have two names, one in Finnish and one in Swedish (the two official languages of the country). The two names are considered equally correct but are not used as a formal duality of names.
A special problem occurs when the landmark lies on the border between two (or more) countries, for example Mount Everest has several different locally-used names.